Hydrodynamic spindle rotating at high speed with axial reciprocation

ABSTRACT

A high-speed hydrodynamic spindle assembly with an axialreciprocation or tacking movement, in which the spindle comprises, in the vicinity of one of its hydrodynamic bearings, a collar which is displaced between two rings and to which is transmitted the hydraulic pressure of the lubricating fluid of the bearings, so as to cause the tacking movement of the spindle, the pressure of the fluid and its regulation being obtained by an appropriate distribution device of the lubricating circuit of the bearings of the spindle.

United States Patent Inventor Jean Beauchet Annecy, France Appl. No. 730,289 Filed May 20, 1968 Patented June 29, 1971 Assignee Societe Nouvelle De Roulements Annecy, Haute Savoie, France Priority May 26, 1967 France 108000 HY DRODYNAMIC SPINDLE ROTATING AT HIGH SPEED WITH AXIAL RECIPROCATION 5 Claims, 3 Drawing Figs.

U.S. Cl 91/35, 416/106, 416/503 Int. Cl F15b 21/02 Field of Search 415/503, 125,131,106;91/35, 39,40

[56] References Cited UNITED STATES PATENTS 2,807,141 9/1957 Strader 91/40 (X) 3,227,049 1/1966 Favrot .1 91/39 3,273,425 9/1966 Hodgson 91/40 (X) 3,475,106 10/1969 Arneson et al 415/503 (X) Primary Examiner-Everette A. Powell, Jr. Attorney-Stevens, Davis, Miller and Mosher ABSTRACT: A high-speed hydrodynamic spindle assembly with an axial-reciprocation or tacking movement, in which the spindle comprises, in the vicinity of one of its hydrodynamic bearings, a collar which is displaced between two rings and to which is transmitted the hydraulic pressure of the lubricating fluid of the bearings, so as to cause the tacking movement of the spindle, the pressure of the fluid and'its regulation being obtained by an appropriate distribution device of the lubricating circuit of the bearings of the spindle.

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PATENTEU JUH29 l9?! HYDRODYNAMHC SPINDLE ROTATING AT lHlllGlhl SPEED WITH AXllAL RECHPROCATTON The present invention relates to a hydrodynamic spindle rotating at high speed with axial reciprocation.

The main constituent pans of a tool-carrier spindle as sembly, for example a grinding-wheel carrier, are the body, the spindle and the intermediate elements such as the bearings, bushes, etc. The bearings of these high-speed spindles are preferably of the hydrodynamic type.

When the tool is used for grinding, it is often necessary to give an axial reciprocation movement to the spindle of the grinding-wheel carrier, this movement being generally known as tacking."

Axial reciprocation or tacking devices are already known, in which this movement is generally obtained by a control which is external to the grinding wheel, in particular by the control of the supporting assemblies of the workpiece or of the grinding wheel: tables or carriages.

in these devices the masses in movement are thus considerable, and the inertia of the corresponding members is also high. This results in the creation of parasitic oscillations which interfere with the movement of reciprocation desired.

The present invention has for its object to provide a spindle assembly which overcomes the above disadvantage, in which the inertia of the masses in movement is reduced to a minimum, and in which the tacking device does not affect the external parts of the spindle assembly, the dimensions' of which remain unchanged.

A spindle assembly of this kind, comprising hydrodynamic bearings, is characterized by the fact that the tacking movement of the spindle is induced by a hydraulic pressure applied to the shaft of the spindle, and is transmitted directly to the tool by this shaft, the pressure and its regulation being ob tained by means of an appropriate distribution device which utilizes the fluid and the supply circuit of the bearings of the spindle.

Other characteristics of the invention will be brought out in the description which follows below of one form of construction of the spindle assembly, given by way of example and without any limitation, reference being made to the accom panying drawings, in which:

FIG. 1 represents an axial section of the spindle coupled to the fluid-supply device;

FIG. 2 is a transverse section taken along the line ll-ll of FIG. 1.

HO. 3 is a perspective view of a variable-thrust ring forming part of the tacking device.

ln FIG. ii, the bored body 1 of the spindle assembly carries a spindle 2 by means of two hydrodynamic bearings 3 and Al, each comprising, as shown in FIG. 2, three bushes 5 supported on the body. End-plates 6 fit into each extremity of the body and ensure a fluidtight seal.

One end 7 of the shaft carries a grinding wheel 8, the other extremity 9 being intended for coupling to the driving device of the too].

On the side of the bearing 4, the shaft comprises a collar 10 adapted to slide in the bore 11 which is an extension of bore for the bearing. Rings 12 and 113 are fixed on the body 1 on each side of the collar and define chambers 14 and 15 around the spindle and form abutments for the axial movement of the collar. The internal diameter of the rings is greater than the diameter of the spindle 2, so as to permit the passage of lubrication fluid towards the bearings.

Conduits 16 and 17 in the body 1 of the spindle assembly put the chambers 14 and 15 into communication with a dis tribution valve it with an open center, of the so-called copying type, through the pipes 19 and 20. The valve 18 is conmeted by a conduit 21 to a pump 22 which takes in the lubricating fluid from a reservoir 23. A pressure-regulation valve 24, connected downstream of the pump, completes the supply circuit.

The valve 118 comprises, in a cylindrical body 25, a cylindrical slide-valve with three bearing surfaces 26, 27 and 28; grooves in the cylinder body form chambers 29, 29 and 29". The central chamber 29 is connected to the conduit 21 of the pump, while the adjacent chambers 23 and 29" are respectively connected to the conduits l9 and 20 which supply the spindle assembly. The rod 30 of the slide-valve is coupled to a crank-arm 31 which is driven by a rotating crankshaft 32 and transmits a reciprocating movement to the slide-valve.

The operation of the above device is as follows:

At the dead center of the crankshaft shown in the drawing, the bearing surface 27 of the slide-valve occupies the central chamber 29 and closes the inlet of the conduit 21!, and the bearing surfaces 26 and 2B are located respectively on the lefthand and the right-hand side of the chambers 29' and 29". When the crankshaft 32 rotating in the direction ofthe arrowf carries out a quarter revolution, the slide-valve is pushed in the direction of the arrowf towards the right, the bearing surface 27 frees the chamber 29 and the inlet of the conduit 21 and closes the chamber 29" and the outlet towards the pipe 20, while the bearing surface 26 occupies the chamber 29' and closes the outlet towards the pipe 19.

The fluid, generally oil, delivered by the pump 22, then fills the chamber 29. At the next quarter revolution of the crankshaft, the slide-valve is driven in the direction of the arrow f towards the left, the bearing surface 26 frees the chamber 29' and the outlet towards the pipe 19, while the bearing surface 27 cxpels the fluid from the chamber 29 through the chamber 29' and the pipe 19 towards the conduit 16 and the chamber 14 of the spindle assembly in which the fluid-pressure increases. Towards the end of this part of the travel, the bearing surface 27 closes the fluid inlet of the conduit 21, and the bearing surface 28 returns to the positionshown in the drawing.

The fluid pressure acts on the annular surface of the collar of the spindle 2 and displaces this latter in the direction of the arrow f until the collar comes into abutment against a hydrodynamic stop created by a wedge of oil in the chamber 15 on the face of the ring 13, the form given to this face permitting the formation of this wedge.

As shown in FIG. 3, this ring 13 and its corresponding symmetrical ring 12 are divided into an odd number of equal radial bearing surfaces 37 by shallow V-shaped slots 38, of which the angle a and the radii R are in relation to the viscosity of the fluid in order to permit the formation of a film of oil capable of withstanding the pressure force of the face of the collar 10 subjected to the tacking forces.

During the third quarter revolution of the crankshaft 32, the slide-valve still moves in the direction of the arrowf the bear ing surface 27 occupying the chamber 29 and closing the outlet towards the pipe 19, freeing the chamber 29 and the inlet of the fluid by the conduit 21 of the pump. During this time, the bearing surface 28 moves and occupies the chamber 29" and closes the outlet towards the pipe: 20. The oil from the pump thus fills the chamber 29.

During the last quarter revolution of the crankshaft 32, the slide-valve is displaced in the direction of the arrowf, towards the right and again takes up the position shown in the drawing. The fluid is then expelled through the pipe 20 towards the conduit 17 and the chamber 15 of the spindle assembly, in which its pressure increases and acts on the annular collar 10 of the spindle 2, displacing this latter in the direction of the arrowf until the collar abuts against a wedge of oil forming an abutment in the chamber 14 on the face of the ring 12. As it moves, the collar 10 forces the oil contained in this chamber through the clearance between the ring; 12 and the spindle 2, and through the groove 33 towards the bearing 3, from which it returns through the conduit 34 and the pipe 35 to the reservoir 23.

Similarly, during the displacement of the collar 10 of the spindle in the direction of the arrow f the oil is driven from the chamber 15 through the clearance between the ring 13 and the spindle 2 and penetrates into the bearing 4 from which it passes through the conduit 36 to return through the pipe 39 to the tank 23.

Thus, the spindle 2 is subjected to an axial reciprocating movement which is the characteristic of tacking and which it transmits to the tool which it carries.

The regulation of the amplitude and the speed of the tacking is obtained by regulation of the flow-rate and pressure of the fluid in the conduits 16 and 17, by means of the adjustment of the copying-valve 18.

I claim:

1. A hydrodynamic spindle assembly in which a spindle is rotated at high speed with axial reciprocation and the resulting movement is transmitted to a tool directly connected to said spindle, comprising a body having inner bores, hydrodynamic bearings fixed in said bores, a spindle carried by said bearings and having a single collar adapted to slide on a first bore in the vicinity of one of said bearings, two independent rings fixed in said first bore and located at each side of said collar, said rings defining a chamber around said spindle on each side of said collar, and a hydraulic distribution circuit connected to said chambers to alternately supply them with pressurized fluid, said fluid forming with said rings hydraulic abutments for said collar, and said fluid in the chambers being utilized for imparting the reciprocating motion to said spindle and for the lubrication of said bearings.

2. A spindle assembly according to claim 1, wherein said first bore containing said rings comprises an extension of one of said bores containing a bearing and communicating with the other bearings.

3. A spindle assembly according to claim 1, wherein said rings have a clearance around the periphery of said spindle to provide communication between said chambers and said bearings.

4. A spindle assembly according to claim 1, further comprising conduits formed in said body enabling said chambers to be put into communication with said distributing circuit, said circuit supplying said chambers alternately and regulating the flow-rate and the pressure of said fluid.

5. A spindle assembly as claimed in claim 1, wherein the surface of said rings facing said collar comprises an odd number of flat radial bearing surfaces alternating with shallow V-shaped slots adapted to permit the formation of wedges of lubricating liquid. 

1. A hydrodynamic spindle assembly in which a spindle is rotated at high speed with axial reciprocation and the resulting movement is transmitted to a tool directly connected to said spindle, comprising a body having inner bores, hydrodynamic bearings fixed in said bores, a spindle carried by said bearings and having a single collar adapted to slide on a first bore in the vicinity of one of said bearings, two independent rings fixed in said first bore and located at each side of said collar, said rings defining a chamber around said spindle on each side of said collar, and a hydraulic distribution circuit connected to said chambers to alternately supply them with pressurized fluid, said fluid forming with said rings hydraulic abutments for said collar, and said fluid in the chambers being utilized for imparting the reciprocating motion to said spindle and for the lubrication of said bearings.
 2. A spindle assembly according to claim 1, wherein said first bore containing said rings comprises an extension of one of said bores containing a bearing and communicating with the other bearings.
 3. A spindle assembly according to claim 1, wherein said rings have a clearance around the periphery of said spindle to provide communication between said chambers and said bearings.
 4. A spindle assembly according to claim 1, further comprising conduits formed in said body enabling said chambers to be put into communication with said distributing circuit, said circuit supplying said chambers alternately and regulating the flow-rate and the pressure of said fluid.
 5. A spindle assembly as claimed in claim 1, wherein the surface of said rings facing said collar comprises an odd number of flat radial bearing surfaces alternating with shallow V-shaped slots adapted to permit the formation of wedges of lubricating liquid. 